The invention relates to the general area of mini-cards that are manufactured in particular from plastic card.
The use of chip cards (smartcards), magnetic cards etc. is currently extremely widespread in daily life. Such cards are used, for example, as bank cards, identity cards, key cards, etc. and can come in various formats, according to their respective uses. As an example, the ID-1 format, with dimensions of 85.60 mm×53.98 mm×0.76 mm, is commonly used for bank cards, loyalty cards etc. For its part, the ID-000 format, with dimensions of 25 mm×15 mm, is the most used format for SIM (Subscriber Identity Module) cards in GSM or UMTS mobile telephones. The ID-1 and ID-000 formats are specified by the ISO/IEC 7816 standard.
The mini-cards of ID-000 format, for example, are generally manufactured from a card in the ID-1 format. To this end, a card body of ID-000 format is created in a card of ID-1 format, with the remainder of the card then acting as a support. The card body is then attached to the support so that it can be detached manually.
FIG. 1A represents an example of a mini-card of the SIM card type as described in the document entitled U.S. Pat. No. 5,936,227 (see. FIGS. 3, 4 and 5 of this document).
In this example, the card (101) is composed of a card body (102) (i.e. the SIM card), the latter being surrounded by a card support (104). Two portions (106A and 106B) of the outer border of the card body (102) act as attachment seams to the card support (104), with the portions (106A and 106B) being located at opposite ends. More particularly, portions 106A and 106B of the border of the card body (102) are weakened regions, each forming an attachment seam between the card body (102) and the card support (104), with these attachment seams being designed to be broken manually.
Attachment seam 106A is formed by a line of weakness. A line of weakness refers here to a line that has been weakened in relation to the surrounding area of the support (110).
Furthermore, portion 106B of the border of the card body (102) comprises a second line of weakness at the junction between a narrow fixing tab (116) and the card body (102). Border portion 106B is also parallel to border portion 106A.
In addition, the outer border of the card body (102) is separated from the card support (104) by two cut-out zones (108A and 108B) which each opens onto the attachment seams (106A and 106B). In other words, the border of the card body (102) is composed of:                border portions 106A and 106B, and        cut-out zones 108A and 108B.        
A line of weakness (110) is also created on the card support (104) so that it is interrupted by cut-out zones 108A and 108B. This line of weakness (110) divides the card support (104) into two support portions, namely portion 104A with attachment seam 106A and portion 104B with attachment seam 106B. Moreover, line of weakness 110 is located close to attachment seam 106B so that, when support 104 is bent along the line of weakness (110), attachment seam 106B breaks totally and easily.
In this document, the breaking of an element (such as an attachment seam or a line of weakness for example) means the total breaking away of this element, unless otherwise indicated in the text. In other words, a broken attachment seam means that the attachment seam in question has totally broken away.
To detach the card body (102) from the card support (104), the user must first bend support portion 104B along the line of weakness (110), thus causing the breaking away of attachment seam 106B (FIG. 1B). Once border portion 1063 of the card body (102) is clear, the user bends the card body (102) along attachment seam 106A in order to break the latter, thus freeing the card body (102) from its support (FIGS. 1C and 1D).
FIG. 2 represents an alternative embodiment that is described in document U.S. Pat. No. 5,936,227 (see FIG. 13). This alternative differs from FIG. 1 in that attachment seam 206B is formed by almost the whole of one of the edges of the card body (202). In addition, the line of weakness (201) created in the card support (204) extends attachment seam 206B.
The card body (202) is detached from the card support (204) in the same manner as that indicated above with reference to card body 102.
The applicant has observed however that the manipulations to be effected in order to detach the card body in FIGS. 1 and 2 can give rise to high mechanical forces on this card body. These forces can then result in irreversible deformation or damage to any flush-mounted metal contacts on the card body for example.
Moreover, the design of cards 110 and 210 show several major defects.
In the case more particularly of card 210, it is necessary that line of weakness 210 should be placed in a median zone of the card support (204), so that the user can easily grasp portions 204A and 204B of the support and bend the latter along line of weakness 210. The configuration of the card (201) therefore does not allow the creation of a card body 202 of relatively large size in relation to the support (204). The relative size of the card body (202) should in fact be moderated in relation to that of the card (201) so that the line of weakness (210) is sufficiently far from the outer edges (214A and 214B) of the card support (204). Typically, the design of card 201 allows the manufacture of card bodies of ID-000 format from a card of ID-1 format.
In addition, so that the card body (202) can be detached easily from its support, the length and/or the robustness of attachment seam 206B must be limited. Typically, the cut-out zones (208A and 208B) run around well over half of the border of the card body (202) in all, which therefore limits the retention of the card body (202) in relation to the card support (204). It is for this reason that the card body (202) possesses a large degree of freedom in the attached position, that is when the card body (202) is attached to the support by the weakened attachment seams (206A and 2068). Thus, the card body (202) is liable to undergo high mechanical forces (bending forces, etc.) in the attached position, during manipulation of the card (201) for example. For example, if a force is applied accidentally at the centre of the card body (202) in the attached position, the latter is liable to be deformed by the bending forces, and possibly to suffer irreversible damage. Moreover, one of the attachment seams (206A or 206B) is liable to break accidentally if the force applied is too high (in particular attachment seam 206B which is shorter and therefore weaker than attachment seam 206A).
The more the cut-out zones (208A and 208B) enclose a higher proportion of the border of the card body (202), the greater the risk of deformation of the card body (202) and/or of accidentally breaking the weakened attachment seams (206A and 206B).
Furthermore, there currently exists a need for a support that allows the creation of a detachable element (such as a card body, for example) that is of relatively large size in relation to the support, while also ensuring good retention of the detachable element and limiting the mechanical forces generated in particular during the detachment of the detachable element from the support.